1. Field of the Inventions
The present inventions are related to display devices such as, for example, projectors.
2. Description of the Related Art
Projectors, which are one type of display device, are used to display images on screens and other projection surfaces. Projectors typically include a light source (such as a lamp) that is turned on as part of the power up process when the projector is turned on, and is turned off as part of the power down process when the projector is turned off. Many light sources operate at a relatively high temperature and, when the projector is turned off, it takes a considerable amount of time (often a few minutes or more) to cool the light source down to the temperature at which it can be turned back on. Accordingly, when a projector is turned off, it cannot be immediately turned back on. This is true even when a cooling fan is used to accelerate the cooling process.
The inability to immediately turn a projector back on after it has been turned off is relatively inconsequential under normal circumstances. However, in those instances where the user turns the projector off prior to the end of a presentation (either by intentionally or inadvertently pressing the power button), the delay can be quite frustrating. One proposed solution is to force the user to confirm that he or she intends to turn off the projector after the power button is initially pressed. More specifically, instead of simply beginning the power down process when the power button is pressed, some projectors will display a message indicating that the user must press the power button a second time in order to initiate the power down process. The projector will remain in this “waiting for confirmation” state until the user presses the power button a second time.
The present inventors have determined that forcing the user to press the power button a second time is a less than satisfactory solution to the inadvertent power down problem. For example, pressing the power button a second time to confirm that the projector is to be turned off can be quite annoying and inconvenient in those instances where the user desires to immediately move on to the next portion of the presentation or meeting, e.g. answering questions or closing sales. Additionally, in those instances in which the user's back is to the projection surface, the user will not see the message. If he or she forgets that the button must be pressed a second time, the projector will continue to shine light on the screen and distract the audience from subsequent portions of the user's presentation.